diff --git a/index.html b/index.html
index 64b8e19..3068816 100644
--- a/index.html
+++ b/index.html
@@ -51,6 +51,7 @@
       <button id="assistantsExportOption" class="menu-item">Export assistants (.json)</button>
       <button id="threadsImportOption" class="menu-item">Import threads (.json)</button>
       <button id="threadsExportOption" class="menu-item">Export threads (.json)</button>
+      <button id="threadsDedupOption" class="menu-item">Deduplicate threads</button>
     </div>
     <input id="importInput" type="file" accept="application/json,.json" class="hidden"/>
   </div>
@@ -101,8 +102,8 @@
 <script src="https://cdn.jsdelivr.net/gh/highlightjs/cdn-release@11.9.0/build/highlight.min.js"></script>
 <script>
 const DEFAULT_MODEL='openai/gpt-4o',DEFAULT_API_KEY=''
-const el=Object.fromEntries(['chat','messages','composer','input','sendBtn','settingsBtnTop','settingsModal','settingsForm','closeSettings','cancelSettings','tabModel','tabPrompt','panelModel','panelPrompt','set_model','set_temperature','set_top_p','set_top_k','set_frequency_penalty','set_presence_penalty','set_repetition_penalty','set_min_p','set_top_a','set_system_prompt','deleteAssistantBtn','sidebar','sidebarOverlay','sidebarBtn','assistantList','newAssistantBtn','userMenuBtn','userMenu','apiKeyOption','assistantsImportOption','assistantsExportOption','threadsImportOption','threadsExportOption','importInput','historyBtn','historyPanel','historyOverlay','historyList','closeHistory','historyMenu'].map(id=>[id,document.getElementById(id)]))
-const clamp=(v,min,max)=>Math.max(min,Math.min(max,v)),num=(v,d)=>v==null||v===''||isNaN(+v)?d:+v,int=(v,d)=>v==null||v===''||isNaN(parseInt(v))?d:parseInt(v),gid=()=>Math.random().toString(36).slice(2,9)
+const el=Object.fromEntries(['chat','messages','composer','input','sendBtn','settingsBtnTop','settingsModal','settingsForm','closeSettings','cancelSettings','tabModel','tabPrompt','panelModel','panelPrompt','set_model','set_temperature','set_top_p','set_top_k','set_frequency_penalty','set_presence_penalty','set_repetition_penalty','set_min_p','set_top_a','set_system_prompt','deleteAssistantBtn','sidebar','sidebarOverlay','sidebarBtn','assistantList','newAssistantBtn','userMenuBtn','userMenu','apiKeyOption','assistantsImportOption','assistantsExportOption','threadsImportOption','threadsExportOption','threadsDedupOption','importInput','historyBtn','historyPanel','historyOverlay','historyList','closeHistory','historyMenu'].map(id=>[id,document.getElementById(id)]))
+const clamp=(v,min,max)=>Math.max(min,Math.min(max,v)),num=(v,d)=>v==null||v===''||isNaN(+v)?d:+v,int=(v,d)=>v==null||v===''||isNaN(parseInt(v))?d:parseInt(v),gid=()=>Math.random().toString(36).slice(2,9),esc=s=>String(s).replace(/[&<>"'`]/g,c=>({"&":"&amp;","<":"&lt;",">":"&gt;","\"":"&quot;","'":"&#39;","`":"&#96;"}[c]))
 const globalStore={get apiKey(){return localStorage.getItem('openrouter_api_key')||DEFAULT_API_KEY||''},set apiKey(v){localStorage.setItem('openrouter_api_key',v||'')}}
 const as={key:'assistants_v1',activeKey:'active_assistant_id',load(){try{return JSON.parse(localStorage.getItem(this.key)||'[]')}catch{return[]}},save(list){localStorage.setItem(this.key,JSON.stringify(list||[]))},getActiveId(){return localStorage.getItem(this.activeKey)||null},setActiveId(id){localStorage.setItem(this.activeKey,id||'')}}
 let assistants=as.load()
@@ -112,7 +113,7 @@ const store=new Proxy({},{get(_,p){if(p==='apiKey')return globalStore.apiKey;con
 const state={messages:[],busy:false,controller:null,currentThreadId:null}
 const getModelShort=()=>{const m=store.model||'';return m.includes('/')?m.split('/').pop():m}
 function reflectActiveAssistant(){const a=getActive();el.settingsBtnTop.title=`Settings — ${a.name}`;if(window.lucide)lucide.createIcons()}
-function renderSidebar(){const activeId=as.getActiveId();el.assistantList.innerHTML=assistants.map(a=>`<button data-asst-id="${a.id}" class="w-full text-left px-3 py-2 hover:bg-gray-50 flex items-center gap-2 ${a.id===activeId?'bg-gray-100':''}"><span class="h-6 w-6 rounded-full bg-gray-200 flex items-center justify-center">🤖</span><span class="truncate">${a.name}</span></button>`).join('')}
+function renderSidebar(){const activeId=as.getActiveId();el.assistantList.innerHTML=assistants.map(a=>`<button data-asst-id="${a.id}" class="w-full text-left px-3 py-2 hover:bg-gray-50 flex items-center gap-2 ${a.id===activeId?'bg-gray-100':''}"><span class="h-6 w-6 rounded-full bg-gray-200 flex items-center justify-center">🤖</span><span class="truncate">${esc(a.name)}</span></button>`).join('')}
 function enhanceCodeBlocks(root){root.querySelectorAll('pre>code').forEach(code=>{if(code.textContent.length>200000)return;const pre=code.parentElement;pre.classList.add('relative','rounded-xl','border','border-gray-200');if(!pre.querySelector('.copy-btn')){const btn=document.createElement('button');btn.className='copy-btn';btn.textContent='Copy';btn.addEventListener('click',async e=>{e.stopPropagation();try{await navigator.clipboard.writeText(code.innerText);btn.textContent='Copied';setTimeout(()=>btn.textContent='Copy',1200)}catch{}});pre.appendChild(btn)}if(window.hljs&&code.textContent.length<100000)hljs.highlightElement(code)})}
 const md=window.markdownit({html:false,linkify:true,typographer:true,breaks:true})
 function renderMarkdown(node,text){node.innerHTML=md.render(text);enhanceCodeBlocks(node)}
@@ -133,7 +134,7 @@ const idb={db:null,open(){return new Promise((res,rej)=>{const r=indexedDB.open(
 let threads=[];const titleFrom=t=>(t||'').replace(/\s+/g,' ').trim().slice(0,60)||'Untitled'
 async function ensureThreadOnFirstUser(text){let needNew=!state.currentThreadId;if(state.messages.length===0)state.currentThreadId=null;if(state.currentThreadId){const existing=await idb.get(state.currentThreadId);if(!existing)needNew=true}if(!needNew)return;const id=gid(),now=Date.now();const th={id,title:titleFrom(text),pinned:false,createdAt:now,updatedAt:now,messages:[]};state.currentThreadId=id;threads.unshift(th);await idb.put(th);await renderHistory()}
 async function persistThread(){if(!state.currentThreadId)return;let th=threads.find(x=>x.id===state.currentThreadId)||await idb.get(state.currentThreadId);if(!th)return;th.messages=[...state.messages];th.updatedAt=Date.now();th.title=titleFrom(th.messages.find(m=>m.role==='user')?.content||th.title);await idb.put(th);await renderHistory()}
-function historyRow(t){return `<div class=\"relative flex items-center gap-2 px-3 py-2 ${t.pinned?'bg-yellow-50':''}\"><button data-open-thread=\"${t.id}\" class=\"flex-1 text-left truncate\">${t.pinned?'📌 ':''}${t.title}</button><button data-thread-menu=\"${t.id}\" class=\"h-8 w-8 rounded hover:bg-gray-100 flex items-center justify-center\" title=\"More\"><i data-lucide=\"more-horizontal\" class=\"h-4 w-4\"></i></button></div>`}
+function historyRow(t){return `<div class=\"relative flex items-center gap-2 px-3 py-2 ${t.pinned?'bg-yellow-50':''}\"><button data-open-thread=\"${t.id}\" class=\"flex-1 text-left truncate\">${t.pinned?'📌 ':''}${esc(t.title)}</button><button data-thread-menu=\"${t.id}\" class=\"h-8 w-8 rounded hover:bg-gray-100 flex items-center justify-center\" title=\"More\"><i data-lucide=\"more-horizontal\" class=\"h-4 w-4\"></i></button></div>`}
 async function renderHistory(){threads=(await idb.all()).sort((a,b)=>(b.pinned-a.pinned)||(b.updatedAt-a.updatedAt));el.historyList.innerHTML=threads.map(historyRow).join('');if(window.lucide)lucide.createIcons()}
 function openHistory(){el.historyPanel.classList.remove('translate-x-full');el.historyOverlay.classList.remove('hidden');renderHistory()}
 function closeHistory(){el.historyPanel.classList.add('translate-x-full');el.historyOverlay.classList.add('hidden')}
@@ -175,6 +176,7 @@ el.assistantsExportOption.addEventListener('click',()=>{const payload={version:1
 el.assistantsImportOption.addEventListener('click',()=>{importMode='assistants';el.importInput.value='';el.importInput.click()})
 el.threadsExportOption.addEventListener('click',async()=>{const all=await idb.all();dl(`threads-${ts()}.json`,{version:1,threads:all});toggleUserMenu(false)})
 el.threadsImportOption.addEventListener('click',()=>{importMode='threads';el.importInput.value='';el.importInput.click()})
+el.threadsDedupOption.addEventListener('click',async()=>{toggleUserMenu(false);const all=(await idb.all()).sort((a,b)=>b.updatedAt-a.updatedAt);const seen=new Set();let removed=0;for(const t of all){const key=JSON.stringify((t.messages||[]).map(m=>[m.role,m.content]));if(seen.has(key)){await idb.del(t.id);removed+=1;if(state.currentThreadId===t.id){state.currentThreadId=null;clearChat()}}else seen.add(key)}await renderHistory();alert(`${removed} duplicate${removed===1?'':'s'} removed.`)})
 el.importInput.addEventListener('change',async()=>{const file=el.importInput.files?.[0];if(!file)return;try{const text=await file.text();const data=JSON.parse(text);if(importMode==='assistants'){const list=Array.isArray(data)?data:(Array.isArray(data.assistants)?data.assistants:[]);if(!list.length)throw new Error('No assistants');assistants=list.map(a=>({id:a.id||gid(),name:a.name||'Imported',settings:Object.assign({model:DEFAULT_MODEL,temperature:1,top_p:1,top_k:0,frequency_penalty:0,presence_penalty:0,repetition_penalty:1,min_p:0,top_a:0,system_prompt:''},a.settings||{})}));as.save(assistants);as.setActiveId(data.activeId&&assistants.some(x=>x.id===data.activeId)?data.activeId:assistants[0]?.id||null);renderSidebar();reflectActiveAssistant();state.currentThreadId=null;clearChat();alert('Assistants imported.')}else if(importMode==='threads'){const arr=Array.isArray(data)?data:(Array.isArray(data.threads)?data.threads:[]);if(!arr.length)throw new Error('No threads');for(const t of arr){const th={id:gid(),title:titleFrom(t.title||titleFrom(t.messages?.find?.(m=>m.role==='user')?.content||'')),pinned:!!t.pinned,createdAt:t.createdAt||Date.now(),updatedAt:t.updatedAt||Date.now(),messages:Array.isArray(t.messages)?t.messages.filter(m=>m&&m.role&&m.content):[]};await idb.put(th)}await renderHistory();alert('Threads imported.')}toggleUserMenu(false)}catch{alert('Import failed')}finally{importMode=null}})
 async function init(){await idb.open();await renderHistory();renderSidebar();reflectActiveAssistant();clearChat();if(window.lucide)lucide.createIcons();fit()}
 window.addEventListener('resize',()=>hideHistoryMenu())